Tortuous occipital emissary vein combined with dural venous sinus stenosis in contrast-enhanced MRV for evaluation of idiopathic intracranial hypertension

Venous outflow impediment is increasingly recognized in idiopathic intracranial hypertension (IIH). We aim to search for the value of tortuous occipital emissary vein (OEV) in IIH by integrating measurable transverse sinus (TS) stenosis in contrast-enhanced MR venography (CE-MRV).

Twenty-one IIH patients were evaluated with CE-MRV. Each patient had high LP opening pressure (> 25 cm.H₂O), and presented papilledema. Age- and sex-matched 21 control subjects who underwent cranial CE-MRV were selected. The OEV and the following features: intraosseous diameter of more than 3 mm, twisted course, and continuous with prominent sub-occipital extracranial veins were named tortuous OEV. TS stenosis was measured by utilizing the coronal T1-VIBE series to calculate quantitative metrics such as TS _max./min.. The tortuous OEV and TS _max./min. were registered to create a bivariate logistic regression model to assess the performance of tortuous OEV for IIH when accompanied by TS stenosis.

Six (29%) tortuous OEVs were observed in the IIH group, while no tortuous OEV was identified in the control group (p = 0.021). The mean TS_max./min. was 2.48 ± 1.19 in patients with IIH and 1.23 ± 0.33 in the control group (p < 0.001). According to regression analysis, tortuous OEV is not predictive of IIH (p = 0.999), while the higher TS_max./min. (> 1.69) is predictive of IIH (p = 0.022, OR: 8.9; %95 CI; 1.4–59.0) when accompanied together.

Tortuous occipital emissary vein is more frequently seen in patients with IIH. However, the tortuous appearance alone does not predict idiopathic intracranial hypertension unless associated with measurable transverse sinus narrowing in CE-MRV.